Encouraged old Rod, the eccentric (8)
I believe the answer is:
exhorted
'encouraged' is the definition.
(exhorting is a kind of encouraging)
'old rod the eccentric' is the wordplay.
'old' becomes 'ex' (prefix meaning former or onetime).
'eccentric' indicates an anagram.
'rod'+'the'='rodthe'
'rodthe' anagrammed gives 'horted'.
'ex'+'horted'='EXHORTED'
(Other definitions for exhorted that I've seen before include "Urged, pressed to" , "Urged or advised earnestly" .)